Log In

Celebrating 45 Years

Follow us on Facebook for all the latest news, updates and promotions


Credit Cards Accepted


Aurora Probability in Northern Canada

Auroral forecast from AuroraWatch.ca


North America Aurora Map from
NOAA Space Weather Prediction Center

Aurora Map - NOAA




pcl-720 image

Digital I/O and Counter Card


Ordering Information

Introduction Return to top of page

The PCL-720 Digital I/O and Counter Card is a PC compatible add-on card with 32 digital input channels, 32 digital output channels and three programmable counter/timer channels.

Its digital I/O channels are TTL-compatible and use 74LS244 driver/buffer circuits to provide higher driving capacity for outputs. These buffered circuits also require lower loading current for input than the regular TTL circuits.

The PCL-720's Intel 8253 programmable timer/counter provides three flexible 16-bit timer/counter channels. You can generate waves and pulses by programming the 8253. Jumper settings determine clock crystal frequency. The PCL-720 also includes a breadboard area perfect for customized circuits.

Applications Return to top of page

  • Digital input
    Contact-closure monitor
    Switch-panel status sensor BCD interface receiver
    Digital signal interface
  • Digital output
    Industrial ON/OFF controller
    Digital signal interface
    BCD interface driver
  • Counter/timer
    Period and pulse-width measurement
    Event and frequency counting
    Waveform and pulse generation

Features Return to top of page

  • 32 TTL digital input channels 3
  • 2 TTL digital output channels
  • High output driving capacity
  • Low input loading
  • Three programmable counter/timer channels
  • User configurable clock source
  • Breadboard area for custom circuits

Specifications Return to top of page

Digital input

  • Logic level 0: 0.8 V max
  • Logic level 1: 2.0 V min.

Digital output

  • Logic level 0: 0.5 V max. @ 24 mA (sink)
  • Logic level 1: 2.0 V min. @ 15 mA (source)

Programmable counter/timer

  • Frequency range: 0 to 2.6 MHz
  • Counters: Three independent 16-bit counters
  • Modes: Six programmable modes
  • Usable pins: CLOCK and GATE for each channel

Clock Source

  • Clock frequency: 2 MHz, 1 MHz, 500 KHz or 250 KHz; jumper selectable
  • Frequency divider: divided by 1, 10, 100 or user adjustable


  • Transfer rate: 300 Kbps typical, 500 Kbps max.
  • Power consumption: 5 V @ 500 mA typical
  • Dimensions: 8" x 3/4" (205mm x 95 mm)
  • I/O port address: Eight consecutive bytes from hex 200 to hex 3F8
  • Breadboard area: 651 (31 x 21) plated-through "donuts", each with a .036" hole on .10" centers

Ordering Information Return to top of page


Digital I/O and Counter Card, user's manual

Screw Terminal Board

24/16 Channel Opto-isolated D/I Board

24/16 Channel Relay Output Board

SSR and Relay Driver Board

Industrial Wiring Kit

Window 3.1 DLL Driver
USA Office

Address: 1480 Gulf Road, Suite 837,
PO Box 1364
Point Roberts, WA 98281

Western Canada - Vancouver BC

Tel:1.800.663.6001 or 1.604.925.6150
Address: 2454 Haywood Ave
West Vancouver, BC V7V 1Y1

Eastern Canada - Markham, Ontario

Tel:1.800.465.0164 or 1.905.513.7027